Display screen or portion thereof with transitional graphical user interface



FIG. 1 is a front view of a first embodiment of a display screen or portion thereof with transitional graphical user interface showing a first image in a sequence, showing our new design;

FIG. 2 is a front view showing a second image thereof;

FIG. 3 is a front view showing a third image thereof;

FIG. 4 is a front view of a second embodiment of a display screen or portion thereof with transitional graphical user interface showing a first image in a sequence;

FIG. 5 is a front view showing a second image thereof;

FIG. 6 is a front view showing a third image thereof;

FIG. 7 is a front view of a third embodiment of a display screen or portion thereof with transitional graphical user interface showing a first image in a sequence, showing our new design;

FIG. 8 is a front view showing a second image thereof; and,

FIG. 9 is a front view showing a third image thereof.

The outermost broken line represents the display screen or portion thereof and forms no part of the claimed design. The remaining broken lines shown in the drawings illustrate portions of the transitional graphical user interface and form no part of the claimed design. The appearance of the transitional image sequentially transitions between the images shown in FIGS. 1-3, between the images shown in FIGS. 4-6 or between the images shown in FIGS. 7-9. The process or period in which one image transitions to another image forms no part of the claimed design. The contrast shown in grayscale in the figures represents a contrast of appearance. 

CLAIM The ornamental design for an display screen or portion thereof with transitional graphical user interface, as shown and described. 